Cameras originally used interchangeable lenses having different focal lengths to give them the ability to form an image of a subject with a selected magnification. Interchangeable lenses are inconvenient in many ways: the lenses themselves can be relatively bulky, the unused lenses need to be stored somewhere and the process of changing from one lens to another can be fiddly and time consuming.
More recently, cameras use a multi-element zoom lens to give them the ability to form an image of a subject with a selected magnification. A multi-element zoom lens uses a relatively complex mechanism to move two or more of the lens elements non-linearly relative to the image plane to keep the image in focus as the focal length of the zoom lens is changed to change the magnification. This mechanism occupies more space than is available in a miniature camera lens.
Miniature cameras having electronic image sensors are incorporated not only in digital cameras but also, more recently, into such consumer electronic products as mobile telephones and personal digital assistants (PDAs). Such products are subject to market pressure to make them ever smaller, or to pack more features into a product of a given size. U.S. patent application Ser. No. 10/741,774 of Schroeder et al. entitled Color Image Sensor with Imaging Elements on Respective Regions of Sensor Elements and U.S. patent application Ser. No. 10/740,935 of Gruhlke et al. entitled Color Image Sensor having Imaging Element Array Forming Images on Respective Regions of Sensor Elements describe a small color image sensor suitable for use in a single magnification digital camera. These applications are assigned to the assignee of this application and are incorporated herein by reference. These applications disclose a single-magnification color image sensor that has multiple sensor and lens combinations, each of which forms an image of the subject in a narrow band of light. This allows the lenses to be physically smaller and located closer to the image plane than a conventional multi-element polychromatic lens, and eliminates the conventional mosaic color filter and its attendant problems.
A market demand exists for a simple, compact color image sensor system having the capability of forming an image a subject with a selected magnification without the need to change a lens or to move lens elements relative to one another in the image sensor system. There is also a market demand for a capability of displaying a picture of a subject at more than one magnification in a consumer electronic product such as a digital camera or cell phone display.